1. Filed of the Invention
The present invention relates to a battery pack, and in particular to a battery pack having, housed therein, a plurality of cells, individually configured by housing an electrode stack and an electrolyte in a box-shaped housing, in a stacked manner.
2. Description of Related Art
In recent trends in downsizing of electronic devices, various batteries used for the electronic devices are also becoming small, having a variety of shapes. Among others, box-shaped lithium ion battery is widely used to mobile phones, notebook-type personal computers and so forth because it can be raised in the energy density.
Battery capacity and voltage adaptive to a wide range of electronic devices can be obtained by stacking a plurality of box-shaped lithium ion batteries in a battery pack. Parallel connection of thus-stacked plurality of batteries also makes it possible to raise battery capacity of the battery pack. Connecting thus-stacked plurality of batteries in series can further raise output voltage of the battery pack.
In this sort of battery pack, insulation between the cells thus arranged in the stacked manner has been accomplished using a partition member such as tape. For example, the insulation between the adjacent batteries has been secured by a gap provided by adhering a tape around the outer peripheral portion of the box-shaped battery housing.
The box-shaped battery is, however, smaller in strength of the battery housing as compared with that of the cylindrical battery, so that the box-shaped battery, such as lithium ion battery, having a large energy density raises a drawback in that the battery housing expands with increase in the inner pressure of the battery, and thereby degrades the durability and reliability.
To address the drawback, Patent Document 1 below discloses a packaged battery device in which the batteries are supported by a spacer having a side plate expansion absorbing space (Patent Document 1: Japanese Patent Application Publication No. 2519576).
Because the side plate expansion absorbing space is given by the spacer between the battery housings of the stacked batteries, the packaged battery devices makes it possible to absorb the expanded portion into the side plate expansion absorbing space even if the side plates of the box-shaped battery housing cause a barrel-shape expansion.